WAGNERS director Denis Wagner has questioned the professionalism of a flood impact review which has provided new perspective on the deadly 2011 Grantham disaster.
An extensive report in The Weekend Australian detailed the findings of a review, which the newspaper commissioned, into the impact a Wagners quarry at Grantham had on the January 10 flood.
The review, by water environment experts DHI, drew different conclusions from those found in a report completed in 2012 by hydrologists from technical professional firm Sinclair Knight Merz.
A significant finding in the DHI report was sections of the embankment wall totalling about 260m had collapsed.
That figure was about five times larger than the 55m breach measured in the 2012 report.
"DHI did not carry out any modelling for the study, but based on our review of the available evidence the embankment could have, in theory, produced a fast moving and temporary change in the onset of flooding which could have impacted on the ability of residents to move to higher ground or safety," the report read.
Its references included Channel 9 helicopter footage from the day of the disaster, an Australian newspaper reporter's 2011 accounts of eyewitness descriptions, a 2014 interview by radio broadcaster Alan Jones and a 2014 statement to Queensland Parliament by then Member for Gaven Dr Alex Douglas.
Sinclair Knight Merz's 2012 report was the basis for the Queensland Floods Commission of Inquiry's finding that none of the earthworks associated with the quarry caused or contributed to the flooding of Grantham.
The DHI report also found irrespective of whether or not the quarry was present, the flood impact at Grantham would have been substantial.
"The peak water levels and velocities that occurred at Grantham would have been similar in both cases with and without the quarry," the DHI report read.
Mr Wagner was in charge of the quarry when the flood hit.
The quarry has since been sold to Boral.
"The engineering firm (DHI) that wrote the report never saw the hydraulic model that SKM did for the flood commission," Mr Wagner said.
"The reason he didn't see the hydraulic model is because he didn't have enough time."
He was annoyed by the way in which the information was presented, but said he would welcome further investigation of the quarry's impact on the flood.
"If there were a review of the flood commission's findings or any element of it we would be more than happy to support that."